Master-follower load sharing in dual winch application
We have an electric motor driven dual winch mechanism to lower and lift a gate. The gate is pivoted at its bottom, lies horizontal when fully opened and vertical when fully closed. The winches are connected to the gate by means of chains on either end through gypsy wheels. I presume this is an elastic coupled system. We had recently installed separate for driving the two winch motors. The operate in master-follower configuration with the follower in speed-controlled mode. The mechanical load on the master-connected side of the gate is high when compared to the other (the tension in the chain at follower side is more while lowering and at master side is more while hoisting). As a result, while closing/hoisting the gate, the master-connected motor slows down (droops). Since the follower is in speed-controlled mode, this reduced speed is the new reference for the follower and the follower also operates in reduced speed instead of trying to speed-up and share the load. The situation is different from that of a conveyor belt where if one motor slows down, then another should also slow down. The same issue happens while lowering the gate also. This time, the master-connected motor operates at normal load whereas the follower motor operates at higher load. How can the load be shared in this case? Can the follower be changed to torque-controlled mode? Will swapping the master and follower solve the problem?
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